Lots of talk here about building airtight houses with mechanical ventilation.

What happens when MVHR, or any other critically necessary high tech solution breaks down and the occupants are either:

1. Too poor to repair or replace it

2. Too stupid to realise it's happened

3. Just don't realise it's significance in the first place

4. Live in a post industrial future that just doesn't offer the option to repair or replace these things.

All this stuff will go the way of the dodo after cheap oil is finished.

I don't think high tech is the future.

Ethics man,

You could have made a further point, being No 5: Turn off the MVHR in order to save energy (then open the windows because the house smells bad). Lots of evidence that this actually happens.

As long as the country has a policy of densification leading to reduction in apparent transport requirements, this type of solution will lead to the most points under the CfSH given the current and proposed Planning Frameworks (in my opinion). So it probably has a good future in the short to medium term, particularly if Nuclear power is seen to be the way to go for generation of power.

In the long term, the solution is likely to work given a power starved future. In other scenarios (little or no power or a power excess) this type of solution may, as you say, may have little merit.

Hi tech stuff

Technology can be a fix, but it has to be appropriate technology. I think you have to remember also that 'technology' doesn't have to equate to complex machines - sometimes, smart use of materials and clever (computer aided?) design can give results that were just not available to 'non-technological' builders.

As it is, using the example of MVHR, the expected lifetime of those units is not that long.I doubt that society will collapse to the point of not being able to fix such things before it would be replaced anyway. If a decline in access to materials and specialist equipment is being experienced, it wouldn't be unreasonable to expect that the next generation of MVHR would be designed to be more easily maintained with a hammer and screwdriver. In other words, if society changes, the technology it uses changes. With relatively few exceptions, I think our building stock shows that change?

The thing is, change is not strictly linear - from mud huts to airtight MVHR homes. If the latter can't be made to work, we're not automatically going to just regress back, we're more likely to experiment with other alternatives.

So I tend to feel that if and when cheap fuel becomes scarce, we'll use different technologies rather than just throwing away our advances and going back to live in mud huts. I rather fancy a nice steam powered CHP chugging away in our shed, but it could just as well be some ultra efficient micro turbine and OLED lighting that keeps the lights on in future.

That said, I agree that MHVR is poor technology - it only appears to do the job expected of it in very specific circumstances which are unlikely to hold for most homes for very long. Sadly, the current design philosophy that informs planning and building regs makes it very difficult to avoid.

Posted By: TunaAs it is, using the example of MVHR, the expected lifetime of those units is not that long.

Citation please?

Posted By: TunaThat said, I agree that MHVR is poor technology - it only appears to do the job expected of it in very specific circumstances which are unlikely to hold for most homes for very long.

Again, citation.

I'm frustrated at the abject luddism displayed here. You'd think that a MHRV was some kind of esoteric and complex device to read what some of you have said. As it is, one could barely conceive of a simpler device: it's an electric motor, a pair of fans and a heat exchanger (usually made of recycled polypropylene) and a couple of filters. Simpler even than a refrigerator - and no-one here would state "oh, fridges, wouldn't want one of those, they don't last very long do they?".

As for poor technology, you obviously have no experience of such systems. They've been in use here in Canada for decades and have been mandated in the building codes for over 12 years. Multi-year research projects have been done on real houses built with typical construction methods to see what, if any, deterioration of the air tightness is - and no problems have been found.

Everything we use requires some kind of maintenance - even "passive" structures. If you want low energy, you can't have your cake and eat it if you also want a reasonable amount of fresh air without the expense and waste of heating the open atmosphere.

Sheesh.

Paul in Montreal.

Paul,

I don't think the problem is in establishing whether or not MVHR works. Canada and Sweden have proved that that it does. It's whether MVHR will work as its designed to do in the UK when it becomes part of our building regulations in around 8 years. Airtight housing and active ventilation are an easy sell when its minus 20°C outside, not so easy here in our relatively mild climate where people sleep with their windows open.

From the chart it does not like much of a crisis either. Scare mongers the lot of you!

Paul, can you tell us who has the rights to the technology to enable the massive expansion in PV post 2020? I wish to purchase shares in this company! What the graph shows may come to pass, lets hope so, but I don't see the evidence for it at the moment so I'd prefer to hedge my bets with a strategy that gives me a certain amount of independence from the grid.

If your heating, ventilation, cooking, lighting and appliances are all dependent on grid electricity (i.e. you don't have your own microgeneration WITH battery storage), if the grid goes down then your house is bearly habitable in the winter months and a total grid failure could take weeks to put right.

In Canada this is an extremely unlikely event given your domestic resources of energy. Not so in the UK. We are increasingly vulnerable to geopolitcal threats by states and by terrorist groups. Personally, I would trade a small amount of energy efficiency in return for more resilience building services.

Would it not be something of a first for mankind to use technology as a means of reducing consumption rather than increasing it? Paul do you type more or less than you did twenty years ago?

Posted By: Paul in Montreal

Posted By: TunaAs it is, using the example of MVHR, the expected lifetime of those units is not that long.

Citation please?

I'm not making claims as to the precise life expectancy of a MVHR, just that I'd expect modern civilisation to hang around slightly longer. I'm not in the camp that expect peak oil to happen on a given date and society to collapse three weeks later :-)

Posted By: Paul in Montreal

Posted By: TunaThat said, I agree that MHVR is poor technology - it only appears to do the job expected of it in very specific circumstances which are unlikely to hold for most homes for very long.

Again, citation.

No citation, just my observation and one that's very specific to the UK. We don't need much heating and ventilation most of the year - in a mild climate, we open the windows, even in the middle of winter. If the heating is running below par, it's quite possible not to notice for some time. Most heating engineers will tell you that they're rushed off their feet when the first hard frost hits in Autumn, because many people have had their heating switched off for the last few months. When the weather changes, thousands of people discover their boiler has packed in.

So if it's used intermittently and we're in a modern building that retains heat relatively well, there's not the incentive to use it properly or maintain it in good condition. I can't find the link to the Canadian Government document that states the required maintenance schedule required to keep MHVR running efficiently, but thorough annual checks are required. In this country we have trouble doing annual checks on our hot water boilers, and they're in constant use.

Paul, my point really was that the vast majority of people in the west take improvements in technology or any efficiency improvements as a reason for further excess, I think it's a cultural phenomenon, from government down we are born and bred consumers (present company excepted). So (a pretty massive) caveat on my earlier comment- I think technology can help enormously, but it needs to be used intelligently, and must be accompanied by a cultural shift from consumption to conservation, reduce reuse recycle and all that...

Posted By: biffvernonMy inspirations come from Blake, Ruskin, Morris and, er, Ben Law.

I'm sure Ben will enjoy the company, seriously though I know where you're coming from, the 'house-in-the-woods' really is a great exemplar. 'Appropriate technology' notwithstanding, I have noted that there do seem to be two schools of though. I would add to the list the CAT in Wales, and the evolution of the Segal method with Architype.

This contrasts with the more number crunching dense concrete approach of those more academically based such as R+B Vale and Sue Roaf.

Indeed often the phrase low energy design seems to be applied to mean universally green rather than the less sound bite friendly 'low environmental impact building' I would prefer to use.

I used to think that the latter school of though was barking up the wrongs tree the idea that for change to occur requires a greater connection with nature and natural materials, until a visit to the Orkney Islands, where I saw some of the earliest settlements in the UK at Scara Brae and some of the cairn structures such as Maes Howe. These structures maintain quite a lot of functionally even after thousands of years... imagine what that does to life cycle analysis figures! Projects such as Hockerton and all its concrete start to stack up more in that kind of context.

Ideally what we would hope to achieve are buildings using natural materials that are truly durable over a much longer timescale that provide for 90% (arbitrary figure) of their energy performance without the technical fixes by virtue of design and materials.

That's the ideal though; in the more every day choices that could still mean high mass concrete or a lighter system built around timber frame...

J

As the standards of work on building site is so poor, all high tech devices installed by building site labour will have a poor reliability record. On failure as the manufacturers will have discovered a cheaper way of making said device, the replacement will not fit. So a failure becomes a re-engineering project by some one who again does not really understand what its all about. And paid for by someone else who does not understand whats its all about.
Still its profits all round and work for the working class. Pity about Joe public.
Frank

Posted By: chuckeyAs the standards of work on building site is so poor, all high tech devices installed by building site labour will have a poor reliability record. On failure as the manufacturers will have discovered a cheaper way of making said device, the replacement will not fit. So a failure becomes a re-engineering project by some one who again does not really understand what its all about. And paid for by someone else who does not understand whats its all about.

Why would the builder install the HVAC equipment? Don't you have sub-trades in the UK that do the specialized work such as plumbing, electrical etc.? Over here in Quebec, all trades have to be licenced for their particular trade.

I can't see how a replacement wouldn't fit - you have four ducts - two inlets and two outlets. It's not rocket science to fit these to any box that has four connectors. I get the feeling that you folks in the UK think that a HRV is some kind of super high-tech device. It's not. It's a box with two fans, four duct connections and some simple filters and a very simple heat recovery core plus a condensate drain. Maintenance is simple too - take the filters out every 3 months and wash them in warm water. Take the heat recovery core out once a year and soak that in warm soapy water. Rinse, repeat and let it dry.

And if your HRV does break down, you can open the windows for a few minutes to get fresh air - or open the door!

Paul in Montreal.